Someone told me that I can open one before April 15 and have it count for the year 2000. Is that the case?

Yes.

How would I technically go about doing this and have my IRA count for 2000 and not 2001, seeing as how we're actually in 2001 now?

You will have to fill out an application form. In most cases, it will ask you to disignate which year you want to apply it too. If you deposit $4000, you will designate $2000 to year 2000, and $2000 to year 2001.

It should be very simple, if it is not, email Financial cafe directly and ask them how to designate the year.